Method and system for light emitting device displays

• US 7,924,249 B2
• Filed: 02/09/2007
• Issued: 04/12/2011
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chaji, G. Reza, Nathan, Arokia
• Primary Examiner(s): Liang; Regina
• Assistant Examiner(s): Sheng; Tom V
• Application Number:
  US11/673,512
• Publication Number:
  US 20070195020A1
• Time in Patent Office: 1,523 Days
• Field of Search: 345 76- 80
• US Class Current: 345/78
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A method and system for light emitting device displays is provided. The system includes one or more pixels, each having a light emitting device, a drive transistor for driving the light emitting device, and a switch transistor for selecting the pixel; and a circuit for monitoring and extracting the change of the pixel to calibrate programming data for the pixel. Programming data is calibrated using the monitoring result.

Claims

1. A display system comprising:

multiple pixels arranged in a matrix of rows and columns, each of said pixels having a light emitting device, a drive transistor for driving the light emitting device, and a switch transistor for selecting the pixel; and

a power supply line for each of said multiple rows of pixels and coupled to said drive transistor in each of said pixels,

multiple select lines for selecting said rows of said pixels in said matrix,

multiple data lines for supplying calibration voltages and display data to said columns of pixels in said matrix,

a current source for supplying current to the drive transistor of a selected pixel via said power supply line or one of said data lines so that said drive transistor functions as a voltage amplifier to produce an amplified voltage that corresponds to a characteristic of said selected pixel that varies with the age of that pixel, said amplified voltage amplifying any shift in said characteristic of said selected pixel, and

circuitry for detecting said amplified voltage and using that detected amplified voltage to determine an adjustment of the calibration voltage for said selected pixel.

2. A display system according to claim 1 which includes a monitoring line and said circuitry includes a sensing network for connecting a path between the light emitting device and the drive transistor to said monitoring line.

3. A display system according to claim 2, wherein the monitoring line comprises a power supply line directly or indirectly connected to the light emitting device or the drive transistor, a data line for providing display data, or an output data line coupled to at least one of the light emitting device and the drive transistor.

4. A display system according to claim 2, wherein the switch transistor of each pixel is selected by a first select line, and wherein the sensing network is activated by a second select line.

5. A display system according to claim 2, wherein the same select line selects the switch transistor and activates the sensing network.

6. A display system according to claim 2, wherein the sensing network comprises a sensing transistor for connecting said path to the monitoring line.

7. A display system according to claim 6, wherein the switch transistor, and the sensing transistor are selected by the same select line.

8. A display system according to claim 2, wherein said sensing network comprises a first sensing transistor and a second sensing transistor for connecting said path to the monitoring line.

9. A display system according to claim 8, wherein the switch transistor is selected by a select line, the first sensing transistor is selected by a second select line, and the second sensing transistor is selected by a third select line.

10. A display system according to claim 8, wherein the first sensing transistor is allocated to each pixel, and wherein the second sensing switch is allocated to more than one first sensing transistor for more than one pixel.

11. A display system according to claim 1 which includes a monitoring line, and wherein each pixel comprises a sensing circuit for monitoring the pixel aging, and wherein said circuitry includes a sensing network for connecting the sensing circuit to said monitoring line.

12. A display system according to claim 11, wherein the sensing network comprises a first sensing transistor and a second sensing transistor for connecting said circuitry to the monitoring line.

13. A display system according to claim 12, wherein the switch transistor is selected by a select line, the first sensing transistor is selected by a second select line, and the second sensing transistor is selected by a third select line.

14. A display system according to claim 1, wherein said pixels form a RGBW pixel array.

15. A display system according to claim 1 which includes a programming line provided to each pixel for providing programming data and monitoring the change of the pixel.

16. A display system according to claim 1, wherein at least a part of the system is fabricated using at least one material selected from the group consisting of amorphous silicon, poly silicon, and nano/micro crystalline silicon, and using at least one technology selected from the group consisting of organic semiconductors technology, TFT, NMOS/PMOS technology, CMOS technology, and MOSFET technology.

17. The display system of claim 1 in which said driver supplies current to a selected row of said pixels at a time when one of the pixels in said selected row is supplied with said calibration voltage.

18. A method of driving a display system comprising multiple pixels arranged in a matrix of rows and columns, each of said pixels having a light emitting device, a drive transistor for driving the light emitting device, and a switch transistor for selecting the pixel, the method comprising

selecting rows of said pixels in said matrix,

supplying calibration voltages and display data to columns of pixels in said matrix,

supplying current to the drive transistor of a selected pixel from a current source via said power supply line or one of said data lines so that said drive transistor functions as a voltage amplifier to produce an amplified voltage that corresponds to a characteristic of said selected pixel that varies with the age of that pixel, said amplified voltage amplifying any shift in said characteristic of said selected pixel, and

detecting said amplified voltage and using that detected amplified voltage to determine an adjustment of the calibration voltage for said selected pixel.

19. A display system comprising:

multiple pixels arranged in a matrix of rows and columns, each of said pixels having a light emitting device, a drive transistor for driving the light emitting device, and a switch transistor for selecting the pixel; and

a power supply line for each of said multiple rows of pixels and coupled to said drive transistor in each of said pixels,

multiple select lines for selecting said rows of said pixels in said matrix,

multiple data lines for supplying calibration voltages and display data to said columns of pixels in said matrix,

an output data line coupled to at least one of the light emitting device and the drive transistor,

a current source for supplying current to the drive transistor of a selected pixel via said output data line so that said drive transistor functions as a voltage amplifier to produce an amplified voltage that corresponds to a characteristic of said selected pixel that varies with the age of that pixel, said amplified voltage amplifying any shift in said characteristic of said selected pixel, and

circuitry for detecting said amplified voltage and using that detected amplified voltage to determine an adjustment of the calibration voltage for said selected pixel.

20. The display system of claim 19 which includes a sensing transistor coupling said data output line to a point between said drive transistor and said light emitting device.